The Internet enables clients or users access to information in ways never before possible over existing communications lines. Often, the client may desire to view and have access to relatively large images. For example, a client/viewer may wish to explore a map of a particular geographic location. The entire map, at highest (i.e., full) level of resolution will likely require a pixel representation to be provided on the display of the viewer that is beyond the size of the viewer screen in the highest resolution mode.
One conventional way to address this limitation is for an Internet server to pre-compute many smaller images of the original image. The smaller images may have a lower resolution (i.e., zoomed-out) views and/or portions of the original image. Most conventional image archive systems use this approach, which is less than optimal since no preselected set of views can anticipate the needs of all users.
Some conventional map engines (see, e.g., URLs http://www.mapquest.com and http://www.MapOnUs.com) use an approach in which the user may zoom and pan over a large image. However, the transmission over the Internet involves significant bandwidth limitations (i.e., the transmission is relatively slow). Therefore, a method and system which allows a realtime visualization of large scale images over a “thinwire” model of computation is needed. In particular, it is desirable to optimize the model which includes an image server and a client viewer connected to one another by a low bandwidth line.
One approach to obtain and utilize multifoveated images in a “thinwire” environment which overcomes the above deficiencies is described in U.S. Pat. No. 6,182,114 entitled “Apparatus and Method for Realtime Visualization Using User-Defined Dynamic, Multi-Foveated Images”. The entire disclosure of this U.S. patent is incorporated herein by reference. This approach provides an effective real-time visualization over a “thin wire” with precision and flexibility, and allows the user to modify the position and shape of the basic foveal regions, the maximum resolution at the foveal region and the rate at which the resolution falls away. In this manner, the “thinwire” model can be optimized. Furthermore, this approach provides for the use of the multifoveated images that can be dynamically (or incrementally) updated as a function of user input. This property is useful for solving the thinwire problem, since it is beneficial for the information to be “streamed” at the rate that optimally matches the bandwidth of the network with the human capacity to absorb the visual information. Thus, dynamic foveation-based rendering (e.g., which transmits image details on demand) can dramatically reduce bandwidth requirements for swift and responsive viewing of the remote documents.
Conventional web servers and other electronic document servers generally do not support foveation. Consequently, the images that are downloaded from these conventional servers tend to travel very slowly over the low-bandwidth links.
A proxy document (e.g., web) server or foveating document server can automatically convert images contained within those pages into the foveated format. The foveating proxy server then transmits the foveated images to a client computer's electronic document viewer (e.g., web browser), and displays the converted pages with the foveated image, instead of the original static images. The foveated images are rendered in a manner that is appropriate for a foveal viewing, whereby the initial low-resolution images are displayed as they are received, and higher-resolution “foveas” are requested, received and updated in response to user input.
However, low-bandwidth communications can still present a significant slow-down for transmission of the images, especially the images embedded within the electronic documents.